ExxonMobil Chemical Co. President Stephen D. Pryor, 64, is retiring Jan. 1 after 44 years of service. Pryor joined predecessor Mobil Corp. in 1971 and in 1993 became vice president of Mobil Chemical Co. He was named president of ExxonMobil's chemical division in 2008. The board is expected to appoint Neil A. Chapman, 52, to run the chemical division. Chapman has served as senior vice president of the polymers division since 2011. The UK native joined predecessor company Esso Chemical in 1984. He was appointed executive assistant to the chairman of ExxonMobil Corp. in 2006 and became president of the global services arm in 2007.